A toner replenishing device for use in an electrophotographic apparatus such as a copying machine, a printer, and other apparatuses supplies toner stored in a vertical hopper to a development device. The toner stored in the hopper is supplied to the development device through a toner supply opening provided in the lower portion of the hopper.
In general, a remaining toner amount detecting sensor is provided inside the hopper. When the amount of toner in the hopper becomes less than a predetermined amount, the remaining toner amount detecting sensor detects the absence of toner, and a message ("REPLENISH TONER") indicating the shortage of toner is displayed on a display section provided on the electrophotographic apparatus.
However, a conventional toner replenishing device has a problem in that in the case of adopting a hopper having a large volume, toner aggregates at the bottom of the hopper due to the dead weight, thereby limiting the amount of toner that can be stored in the toner replenishing device to the amount which does not cause aggregation. Namely, toner can be stored in the toner replenishing device only in the amount of one toner container having a specified volume. For this reason, it is required to replenish the toner in a short cycle before a service person could replenish the toner in his or her regular visit, thus requiring the user to replenish the toner which may be annoying for the users.
Further, since a single remaining toner amount detecting sensor is provided inside the hopper, toner becomes empty shortly after the notice of toner shortage. This causes the following problem. When a large amount of copying, inefficient copying occurs because the copying machine stops while still preparing new toner due to the shortage thereof.